Superhydrophilic membrane coupled with hydroxide ion-assisted bubbles for efficient separation of surfactant-stabilized oil/water emulsions

Developing a feasible and efficient membrane for the purification of surfactant-stabilized emulsions is urgently needed but impeded by the issues of membrane fouling and the inherent trade-off between separation efficiency and permeation flux. A superhydrophilic conductive membrane was developed by coating MXene/carbon nanotubes layer and polydopamine-hydrogel molecular layer, which as cathode integrates feasible hydroxide ion-assisted bubbles on its surface by electrolysis of water. These bubbles are more effective than conventional ones in removing surfactant-stabilized oil droplets because the hydroxide ions significantly promote the aggregation of oil droplets and bubbles by reducing their Debye length. In this way, the oil droplets even the small-sized ones assisted by these bubbles are quickly detached from the membrane surface, avoiding the oil accumulation and penetration, significantly mitigating the membrane fouling and trade-off challenges. Therefore, the membrane has outstanding separation efficiency (99.57 %), permeation flux (2065 L m −1 h −1 bar −1 ), antifouling ability and durability in surfactant-stabilized oil/water emulsion separation. Besides, this membrane coupled with hydroxide ion-assisted bubbles is easily manageable and eco-friendly, which provides a promising solution and valuable insights for efficient emulsion separation and wastewater remediation.